Tool



y 1940- v G. H. GlLMAN 2,209,079

- TOOL Filed July 25, 1939 2 Sheets-Sheet 2 Fga I 11.

Paten ted July 23, l940 George& Gilman, Newark, N. J.

Application July 25, 1939, Serial No. %6,403

14 Claims.

My invention relates to tools, and particularly, but not exclusively, to rock drills.

More' specifically the invention relates to tools comprislng a part for Operating upon the work and a holder which detachably carries said part, such a tool, for example, being exemplified by a rock drill` comprislng a rock drill steel which detachably' carries a rock drill bit.

The invention has among its objects the provision of a detachable part for Operating upon the work as, for example, a detachable rock' drill bit, that may be inexpensively fabricated and maintained in Operating condition with a minimum' of machinng Operations or special equipment. The invention, however, will be best understood from the following description when read in the light of the accompanying drawings, the scope of the invention being more particularly pointed out in the appended claims.

In the drawings:

Fig. 1 represents a vertical section of ground or rock showing rock drills in the process of forming drill holes;

Fig. 2 is a side elevation, on an enlarged scale and with parts broken away, of the lower end of the right hand rock drill of Fig. 1 as viewed from the right;

Fig. 3 is' a side elevation of the lower end of the rock drill according to Fig. 2, with parts broken away; i l

Fig. 4 isa bottom view of the rock drill according to Fig. 2;

Fig. 5 isa diagram illustrating the operation upon the work of the rock drill bit accordingto Figs. 2, 3 and 4; V

Flg. 6 is a perspective oi the lock Washer according to Figs. 2 and 3; a v

' Fig. 7 is a perspective of one of the bit sections of the rock drill according to Figs. 2, 3 and 4;

Fig. 8 is a section on the line-s-s of Fig. 7;

Fig. 9 is an elevation of the lower end of a modified form of rock'drill, withparts broken away;

Fig. 10 is a bottom View of the rock drill according to Fig. 9;

Flg. 11 is an elevation of the lower end f a further modified form of rock drill, with parts broken away; and

Fig. 12 is abottom view oithe rock drill according to Fig. 11.

As will be understood by those skilled in the art, a rock drill commonly comprises a length of drill steel which at one end is provided with a rock breaking or cutting bit, the bit being integral with the steel. It has beenproposed in the interests oteconomy to make such bits -de- 4 tachable from the steel. However, detachable bits heretofore proposed commonly 'have been integral structures which, besides requiring' a forging operation .roughly to shape them, have 5 required expensive machining Operations tofinish and reshar'pen them, this resharpening operation commonly necessitating the use of expensive facilities not ordinarily possessed by the occasional user of rock drills, and as'detachable 10 drill bits have their greatest potential application with such usersjthe u'se of the same heretolere has been seriously restricted The present invention seeks therefore 'to provide, among other things, a detachable rock drill 15 bit which, among other things, will avoid the above mentioned objections'. The invention however is not limited to rock drilIs or detachable rock drill bits, but may be applied to other forms of tools having' detachable parts for Operating 0 upon the work.

`Referring to the'drawings, a rock drillaccord ing to the invention ma comp'rise a steel which, without limitation thereto; maybe a round steel l or a hexagonal steel 3, or tli steel may have 2 any other suitable cross-sectifial shape as will be understood by thoseskilled in .the art. "These steels, which are adapted to extend into the drill hole H, are formed at their upper endswith suitable shanks 5 adapted to be received by the chuckfof. a rock drilling engine', and at their lower ends carry detachable drill bits 1." The drilling engine, as will be `understood by 'those skilled in the art, operates upon the shank end of the steel by percussion, and also commonly rotates the steel, so as to cause the bit, to operate upon the'work and properly form the drill hole.

As illustrated'in Figs. 2 to`4, the detachable bit 'l is provided `at one end with a coarsely screw-threaded shank portion 9,-which latter is received ina socket ll provided withinternal screw-threads complementary to those" 'on' the shank, the socket opening on the 'end of the tool holderconstituted by the drill steel. This socket, 45

which as ,heret'ofore may be formed integrally the bottom wall |3 of the socket so thatthe 55 thereoi;` beyond that end constitutes a socket, in 50 screwing of the bit out of the socket ll. such' lock washer however ordinarily may be omitted on 'account of the screw-threads on'the shank of ,the bit being pitched in such direction thatthe rotation of the rock drill tends to screw the shank of the bit into the socket.

In the bit illustrated' by Figs. 2, 3 and 4, the forward end of' the drill bit is formed with a pair of parallelly disposed chisels -2I having cutting or 'rock breaking edges 23 and reaming edges 25. A bit so formed will cause the chisel edges 23 to break or cut the rock on a series of pairs of parallel lines as indicated in Fig. 5 at a. As the rock drill is relatively slowly rotated, as. compared to the rate blows are imparted to-it by the drilling engine, these parallel. lines of cutting will act on the rock at the bottom of the drill hole along' a multitude of intersecting lines, as indicated in Fig. 5; and eflectively remove the rock sc as to advance the drill hole. 4 4

As illustrated by Figs. 2 and 3, the bit is'split longitudinally thereof on a plane disposed diametrically with relation to the shank 9, as indicated at 2'| inFlgs.Z3 and 4, to divide the bit into two identical sections each having a chisel ZI, while so that the shank portions of the sectionsmay be identical the shani: is provided with two parallel relatively interposed' screw-threads 29 andxsl, that is to say a `so-called "double thread.

In respect to the above paragraph, it will be `understood that were. a single screw-thread employed for the shank the shank portions of the two sections of the drill bit would not be identical. By having two screw-threads which :intersect a given plane normal to the axis of the bit at points diametrically opposite each other each' section in respect to its screw-threads may be made identical. Were the shank split lqngitudinally into three sections by planes disposed ra-- dially of the bit and angularlyspaced l20 a'part. as would be convenient with the common form of bit having three equally spaced chisel edges radiating' from the axis of the bit.it would be necessary to have three parallel relatively interposed screw-threads, that is to say a 'so-called "trime-thread," to make the 'shank portions of the sections identical in respect to their screw- 'threads' Likewise with the' common so-vcalled,

"cross bit"-which has four equally spaced chisel edges radiating from the axls of the bit the latter could be split on planes radiating from said axis each midway pairs ofadjacent chisel edges,

'and in such case the shank of the bit must be provided with 'four parallel relatively interposed screw-threads, that 'isto say a so-called "quaddruple thread," to make the sections identical in respect to their screw-threads. In all of these cases each series of screw-threads in respect to a given' plane transverse to the axis of the bit should follow paths which intersect that plane at`points which are an'gularly spaced the same terposed screw-threads corresponding in number to thosesections, the screw-threads being s'o positioned that each section in 'respect to its screw-threads will be substantially identical.

As is` conmon practice, each of the drillsteels illustrated is provided with an axial bore 33 through 'which water or air, or both, may be supplied from the drilling engine to discharge at the bottom of the drill hole. This bore 33 opens into the socket il and is continued by the bore 35 ot the drill bit to the front end of the latter,'

as clearly indicated by Flas. 4 and 7.

"As shownin Flgs. 2, 3, 4 andfl, each section of the drill bit is provided with a -projecting lug '31 on its surface which abuts the other section, and is also provided with a recess 39 for receiving the lug 31 of the adiacent section. This construction acts to lock the sections together and facilitates assenbling them in proper relation to each other. Referring particularly to the drill bit above described, it will be observed that each 'section of said bit may be readily forged, say by a "drop forging" operation employing a single pair of' cooperating' dies, to 'reider it suitable for use without further maehining operations except Srinding the faces of the chisel to sharpen it. It would' not be possible to do this in any simple way were the drill bit an integral structure, it being necessary, for example. with an 'integral structure to forse the bit by use of several palrs of dlii'erently 'shaped dies, to bore in the 'bit the axial hole for passage of air and water,` and to form the screw-threads on the shank of the bit by a machining operation It is entirely feasible however to forge' the screw-threads on a part which has a circumfei'ential extent of not more than such as that illustrated, without forming burs on the threads. and in this &connection it will be understood that the end portions ot each turn of the screw-threadson each section may be bevelled as'a result' oi the forging operation, as indicated ai:` li (Fig. 8), or otherwise shaped to prevent such burrin: as a result of 'that operation. 5 v

Further, as will be clear from Flas. 3 and 4, the chisel parts of each bit section may be readily ground'by use-ofsimple grindin'g apparatus, say` by.use of the ordinary cylindrical disk emerywheel, which would not'be possible were the bit an integral structure as will be readily apparent e when it is observedgthat the two chisel parte in any two to be assembled to form the bit without 'the necessity 'of matching the sections,- and at the same time the bit'may be removed from the steel and the sections thereoi' resharpened` in the ileld'by'use of the ordinary grindin'g appa-- ratus with which the user is commonly equipped,

and the resharpened hits may be reassembled withoutthe necessity oi' matching parts. Again it will be obvious that with a bit so constructed damage to 'one section does "not prevent continued use .of the other section, whereas were the bit integrally constructed breakag'e of one chisel, for example, might necessitate discarding the entire bit. 4

It will be understood that other forms and arrangements of chisels may 'be employed besides those above referred to as, for example, that shown in Figs. 9 and 10 iri-which the chisels ti are of arcuate shape. O therwise this bit may aaoopvg he identical with that shown by Figs. 2, 3 and 4. However, as illustrated in Fig. 9, the washer !5, instead of being placed at the outer end of the socket which i receives the drill bit shank, is placed in the socket at 'the rearward end of that shank, while the shoulder s of-the bit bears against the forward surface l'l of the socket to cause the blows imparted to the drill steel to be efectively conveyed to the bit. -The Washer l5 in this case, if desired, may be placed in an annular enlargement 41 at the inner end of the bore of the socket for permanently retaining the washer in place even upon removal of the hit.

It will be understood that the drill bit sections so far described, although identical in respect to the screw-threads of the shank portions thereof, need not be identica' in respect to their chisel portions even though interchangeable with each other. In other words, drillhit sections having different shaped chisels may be assembled with each other as, for example, a section according to Figs. 2, 3 and 4 with a section according to Figs. 9 and 10 to give the drill bit shown by Figs. 11 and 12. A bit formed with sections having' different shaped chisels may be deliberately employed in situations where the cutting properties of the bit are improved thereby. otherwise the arrangement may be employed in emergencies where the desired number of sections having like chisels are not available.

It will he understood-that according to the invention the detachable drill bit or other tool is split into longitudinal sections, which sections in respect to at least the interrupted plural screwthreads of the shank portions thereof are substantially identical, while the socket which receives the shank of the assembled drill bit is provided with internal screw-threads `corresponding in number to and complementary with the plural screw-threads of said shank. Further, these sections, although otherwise not necessarily identical, nevertheless are' so constructed that they are interchangeable in the sense that for any section may be substituted a section identical with any other section, in which sense the word "interchangeable" is used in the appended claims. It will be clear that it would be impossible to have the sections' interchangeable in that sense were they so formed that the shank of the assembled drill bit or other tool presented a "single"screw-thread.

It will be understood that, within the scope of the appended claims, wide deviations may be made from the forms of the invention described without departing from the spirit of the invention.

I claim:

1. A tool comprising a part for Operating upon the wo k and a holder for said part, said .holder having a socket portion and said part a shank portion received by said socket portion, which shank portion is provided with a plurality of external parallel relatively interposed screwthreads and which socket portion is provided with a like number of complementary internal parallcl relatively interposed screw-threads, the screw-threads of' one portion cooperating with those of the other portion'whereby said part may be detachably secured to said holder, said part being split longitudinally of the screwthreaded shank portion` thereof into a plurality of entirely separate sections correspondlng in number tothe threads on' the screw-threaded shank portion thereo, which sections are interchangeable with each other and in respect at least tothe screw-threads thereof are substantially identical. 4 I 2. A tool according .to claim 1 in which each section is provided with an instrumentality for.

Operating upon the work.

3. A tool according to claim 1 in which the sections are provided with complementary, means acting to lock them together.

4. A tool according to claim 1 in which each section is provided with an instrumentality for Operating upon the work, the sections being provided with complementary means acting to lock them together.

5. A tool according to claim 1 in which the holder is a drill steel operatively carrying the socket portion, with .the socket opening on an end thereof, the part for Operating upon the work being a detachable rock drill bit the screw-threaded shank portion ofwhich is received by said socket, each section of said bit havinga rock cutting chisel on its end opposite said shank portion.

6. A tool according to claim 1 in which the holder is a drill steel operatively carrying the socket portion, with the socket opening on an end thereof, the part for Operating upon the work being a detachable rock drill bit the screwthreaded shank portion of which is received by said socket, each section of said bit having a rock cutting chisel on its end opposite said shank portion, the sections having complementary means acting to lock them together.

7. A sectional' element of a tool adapted to be assembled with one or more other sectional elements interchangeable therewith to form a completed tool part for Operating upon the work, said element having a shank portion which is a segment of a shank of circular cross-section provided with a plurality of external parallel relatively interposed screw-threads, the segment being such that a plurality thereof equal in number to said screw-threads may be assembled toform said shank.

8. A sectional element according to claim '7 in which the shank portion is substantially a segment of a shank of circular cross-section.

9. A sectional element according to claim '7' having, at its end opposite the shank portion thereof, an instrumentality for Operating upon the work.

10. A sectional element according to claim 7 having means adapted to interlock with complementary parts on another' sectional element to be assembled therewith, and also having like complementary parts adapted to interlock with like means.

11. A sectional element of a detachable rock. drill bit adapted to be assembled with 'one or more other sections interchangeable therewith to form a completed drill bit, said element having at ne end a shank portion which is a segment of a shank of circular cross-section provided with a plurality of external parallel relatively interposed screw-threads, and having at its opposite 'end a chisel for Operating upon the rock, the segment being such that a plurality thereof equal in number to said screw-threads may be assembled to form said shank.

12. A sectional element according to claim 11 in which the shank portion is substantially a 180 segment of a shank of circular cross-section.

13. A sectional element according to claim '11 having means adaptedto interlock with complementary parts on another sectional element to be assembled therewith, and also having like comtially a. 180 segment o! a shani: oi circuiar crosssection provided with a 'double screw-thread, and

having ai; its other end chisel means symmet-' ricaly disposed with relation to a. plane which both includes the axis of such shani: and is 'noi:- mal to that plane which also' includes said azis' 5 and deflnes said 180 segment; I

. GEORGE H. GIIMAN. e 

